Synergistic effect of eco-friendly pistachio shell biomass on nano-MnO2 for crystal violet removal: kinetic and equilibrium studies

Abstract

Pistachio shell powder-supported MnO2 nanostructure-based eco-friendly nanocomposite (nMPP) was prepared via one-pot redox precipitation method and was characterized by FTIR, XRD, SEM, TEM, BET, TGA/DTA, and XPS techniques. SEM and TEM analysis revealed the pseudo-spherical and nanorod morphologies of the synthesized nano-MnO2 and found agglomerated on the pistachio biomass. The nMPP contains nearly 41% Mn as MnO2 (w/w %) dispersed onto the pistachio shell biomass as confirmed from EDX, TGA, and AAS analysis. The nMPP exhibits multi-process crystal violet (CV) removal phenomenon under different pH of aqueous dye solution. Under acidic pH, nMPP caused oxidative degradation of CV by in situ formed.OH radicals; while under the neutral pH, CV undergoes monolayer adsorption onto the surface of nMPP as confirmed from Langmuir adsorption isotherm fit with maximum equilibrium adsorption value of 148.7�mg.g?1. The nMPP nanomaterial exhibits a synergistic effect between adsorption efficiencies of pistachio shell biomass and nano-MnO2 for the effective removal of toxic CV dye. The maximum saturation adsorption and rate constant (k 2) value obtained from the pseudo-second-order kinetic fit model were 119.13�mg.g?1 and 5.0 � 10�4�g.mg?1�min?1, respectively. Graphical abstract: [Figure not available: see fulltext.] � 2022, The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University.